android - Flutter android 应用程序 - android.support.v4.content.FileProvider 未找到

Question

Flutter android 应用程序，我想下载并写入文件，但出现此错误:

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.ProviderInfo.loadXmlMetaData(android.content.pm.PackageManager, java.lang.String)' on a null object reference

因此，为了解决上述错误，我添加了提供程序和 xmlfile 及其依赖项，但现在我收到错误，找不到“android.support.v4.content.FileProvider”

<application> 
<provider
  android:name="android.support.v4.content.FileProvider"
  android:authorities="${applicationId}.provider"
  android:exported="false"
  android:grantUriPermissions="true">
     <meta-data
          android:name="android.support.FILE_PROVIDER_PATHS"
          android:resource="@xml/provider_paths" />
</provider>
</application




 implementation 'com.android.support:support-v4:28.0.0'
    implementation "com.android.support:appcompat-v7:28.0.0"
    implementation "com.android.support:design:28.0.0"
    implementation 'com.google.firebase:firebase-core:16.0.9'
    implementation "com.android.support:support-core-utils:28.0.0"

Answer 1

是的，我解决了

我想写入文件，这就是我添加 <provider></provider> 的原因但我以简单的方式编写我的文件，所以我删除 <provider>从那里标记

我使用以下方式写入文件:

final response2 = await http.get(url);
var bytes = response2.bodyBytes;
var dirc = Directory("/storage/emulated/0/MyFiles");
if(dirc.exists()!=true){
  dirc.create();
}
File file = new File('${dirc.path}/$filename');
var newFile = await file.writeAsBytes(bytes);
await newFile.create();
if(newFile.exists() != null) {
  print("file create successfully");
  // showNotification  
}

you should ask storage permission before write file